The present invention relates to semiconductor devices, and more specifically, to carbon nanotube transistors.
Carbon nanotube field-effect transistors (CNTFETs) are strong candidates to replace or supplement traditional silicon transistor technology. CNTFET performance may be significantly affected by the electrical resistance of the contacts. Therefore, the overall contact area between source/drain electrodes and CNT affects the performance of the CNTFET.
In order to avoid high contact resistance limiting the overall transistor performance, conventional CNTFETs requires a large length (Lc) of the metal contacts in a direction parallel to the gate length (LG) (i.e., in the X-axis direction), as illustrated in FIG. 1. Recent device scaling trends continue to demand a reduction in the pitch of semiconductor device, which is defined as the distance between the center of the gates of two adjacent devices. When fabricating multi-gate CNTFETs, a minimum distance (dC) between adjacent metal contacts is required to prevent shorting of adjacent semiconductor devices. Therefore, a device structure that has an increased length of the metal contacts without increasing the overall pitch of the semiconductor is desirable in order to ensure a suitable dC.